The present invention relates to a sensor for detecting the leakage of a corrosive liquid, more particularly, to a leaking liquid sensor which is capable of accurately and quickly detecting leakage of a liquid which may occur from a pipeline transporting a corrosive liquid such as a strong acid or alkaline liquid.
In a chemical plant or the like, where large quantities of strong acids such as hydrochloric acid and nitric acid or strongly alkaline liquids such as aqueous solutions of caustic soda are used, it is general practice to transport each of these liquids through a pipeline. In such a transportation system, if leakage of such a corrosive liquid is not detected, the leaking liquid may corrode equipment located near the leakage, or it may result in an accident. It is therefore essential to develop a sensor which can detect leakage of such a corrosive liquid.
Although there is no known sensor which exactly corresponds to the sensor of this type, a cable-like sensor for detecting leakage of an electrically conductive liquid has been proposed, in, for example, the specification of Japanaese Utility Model Laid-Open No. 96248/1983 under the title of "Sensor for Detecting Conductive Liquid" and of Japanese Utility Model Laid-Open No. 167436/1983 under the title of "Leaked Liquid Detecting Wire".
These conductive liquid detecting sensors, however, have a disadvantage in that water droplets and condensation can result in errors because these sensors detect a leakage by detecting conduction between electrodes or a drop in the resistance between electrodes.
In view of the disadvantages of the prior art described above, it is an object of the present invention to provide a sensor for detecting a leaked liquid which is capable of selectively detecting the leakage of a corrosive liquid such as alkaline or acid liquid both quickly and accurately, and which does not generate errors when in contact with water.